It is proposed to conduct a rigorous study of Na-dependent anionic amino acid transport in giant axons, of the squid Loligo pealii and of the marine worm Myxicola infundibulum, utilizing the techniques of internal dialysis and voltage clamp. The study seeks to: (1) establish the kinetics of influx and efflux with respect to the amino acids and Na; (2) measure directly the flux coupling of Na and amino acid; (3) determine the dependence of kinetic parameters on membrane potential; and (4) establish the dependence of kinetic parameters on ATP.